The present invention relates to a filter apparatus for filtering a liquid containing solid materials, such as cutting oil and machining oil, so as to separate these solid materials from the liquid.
At factories, used cutting oil or machining oil contains a large quantity of chips and abrasive grains. In order to put such cutting oil or machining oil to reuse, the chips or abrasive grains must be separated from it. A filter apparatus is widely known as an apparatus which separates solid materials such as chips from a liquid such as cutting oil.
The filter apparatus generally has a filter with a number of through holes. Filtration performance is improved as these through holes are smaller. However, if the holes are smaller, they are easily clogged, resulting in a great decrease in the filtration rate of the liquid. In order to prevent such clogging, the filter must be frequently cleaned.